Dependence of surface tension of fruit puree on temperature exposure

When developing food products with new properties using innovative technologies, it is important to obtain data on the physicochemical, thermal-physical and structural-mechanical properties of the processed food media. So, one of the key components in the selection of the mode of collapsing ultrasonic cavitation is the surface tension of vegetable purees. The paper presents research data (2020) on the effect of temperature on the surface tension coefficient of fruit puree of different viscosity. The objects of research are cherry plum, pear and apple puree, combined in a row by viscosity. The surface tension coefficient was determined by the stalagmometric method, for which the puree was preliminarily centrifuged. The measurements were carried out at temperatures of 25 and 35 °С. It was found that, under equal conditions of centrifugation of puree, the proportion of supernatant in pear puree is noticeably higher – 77.37 % to the weight of puree in comparison with cherry plum puree (67.20 %) and apple puree (52.75 %). This fact can be explained by the presence of stony cells in the former which form an incompressible sediment, which allows a greater separation of the dispersed phase (sediment) and the dispersion medium (supernatant). It was found that the coefficient of surface tension of fruit purees, despite the slight difference, decreases with increasing temperature. Analysis of the steepness of the slope of the curve characterizing the effect of temperature on the surface tension coefficient showed that temperature stabilization during technological processing is more required for pear puree.

Improving marshmallow production technology by adding the fruit and vegetable paste obtained by low-temperature concentration

A formulation composition and a low-temperature technique have been devised for concentrating fruit and vegetable puree with the following component content: 20 % apple; 20 % pumpkin; 15 % beets; 15 % cranberries; 15 % hawthorn. The puree is concentrated in a rotary evaporator to a solids content of 50 % at a temperature of 50...56 °C under vacuum. The processing time was reduced to 1...2 min, which is several times less compared to conventional single-case pump vacuum evaporators (60...90 mins). Reducing the temperature influence of concentrating contributes to an increase in the organoleptic and physicochemical parameters of the resulting paste. To determine the effect of the contribution of each component to the structure of the paste, the structural and mechanical properties of the puree from each raw material and concentrated semi-finished products were investigated. The devised paste has an increased strength of the structure with a dynamic viscosity value of 394 Pa⋅s, which is 2.5 times more than that in the control sample. The devised blended fruit and vegetable paste has an increased content of physiologically functional ingredients and good organoleptic parameters, unlike control (apple paste). It was established that the partial replacement of apple puree in the formulation composition of marshmallow with 75 % of the devised multicomponent fruit and vegetable paste gives the product original properties. The dynamic viscosity value of the marshmallow in which 75 % of apple puree was replaced with the devised paste has increased, compared to the control sample (marshmallow without additives), from 408 Pa⋅s to 908 Pa⋅s. The color of the marshmallow mass where 75 % of apple puree were replaced is bright pink with a wavelength of 596.7 nm and a brightness of 62.3 %. The data reported here make it possible to improve the quality of original marshmallow products when adding fruit and vegetable semi-finished products whereby an increase in functional properties is provided

Phloridzin as a marker for evaluation of fruit products authenticity

Phloridzin (phloretin-2'-O-glucoside) is a phenolic compound characteristic of the genus Malus. This study aimed to evaluate phloridzin as a marker of undeclared addition of apples in fruit products. To test this proposal, the heat and oxidation stability of phloridzin was firstly confirmed. Then the distribution and variability of phloridzin in apples were studied, showing no difference between the tested apple varieties (Golden Delicious, Granny Smith, Rubin and Champion) but a significant difference in phloridzin content in seeds (2 380 ± 755 mg kg^–1) compared to peel, flesh and core, which contained less than 70 mg kg^–1. The effects of different stages of apple purée production at an industrial scale were also investigated. The kinetics of phloridzin diffusion from seeds to apple homogenate played an important role in the final phloridzin content in 16 analysed apple purées (26–39 mg kg^–1). Finally, the survey of phloridzin content in 31 fruit products in the market was carried out. Phloridzin was also measured in eight jams and fillings which did not declare the presence of apples on their labels; findings from 2 to 6 mg kg^–1indicate the addition of apples from 5% to 20%. It was confirmed that phloridzin appears to be a suitable marker for detecting the undeclared presence of apples, which are a cheap substitute for the declared fruit types.